This invention relates to polymeric compositions having the unique ability of providing necessary and desirable properties for skin contact, i.e., breathability, tack, resistance to leakage, dissolution, and disintegration by fluids, and cohesive strength. More particularly, the invention relates to a self-supporting adhesive composition which may be utilized in fabricating a wound dressing, external catheter strip, male exterior catheter, electrode swatch, or a sealing gasket for an ostomy appliance or like medical device. As it is self-supporting, the composition of the invention may be used by itself as a medical device or may be laminated to other materials to fabricate a medical device.
The preparation of medical adhesives which are sufficiently adherent to resist body fluids yet which are sufficiently comfortable has been a difficult proposition. One such adhesive is disclosed in U.S. Pat. No. 3,339,546 and includes a mixture of a viscous gum-like substance and a water-soluble or water-swellable hydrocolloid. The adhesive is applied to a backing and used as a bandage or tape.
A breathable adhesive tape for medical purposes is disclosed in U.S. Pat. No. 4,427,737. This tape includes a porous backing layer and a microporous adhesive comprising a pressure-sensitive rubbery elastomer having dispersed therein a viscous gum-like substance.
Ostomy appliance pads present an especially difficult problem in formulation due to their exposure to body fluids which cause degradation and their need to provide a firm seal to prevent odors. Karaya powder has long been used as an ostomy adhesive, and ostomy appliance pads based upon the inclusion of Karaya powder, such as are disclosed in U.S. Pat. No. 3,302,647, are currently in general use. Karaya has certain disadvantages since it is a nutrient substance and capable of supporting the growth of micro-organisms, not only in use, but when contaminated in storage prior to use. Karaya compositions are lacking in cohesiveness, and therefore tend to disintegrate as well as become slippery when wet often times necessitating the use of a special adhesive to prevent dislocation from the ostomy site.
In U.S. Pat. No. 4,160,076, there is disclosed hydrophilic foams prepared from a capped polyoxyalkylene polyol reactant having a defined average reaction functionality greater than 2, an aqueous reactant and a carefully balanced combination of a nonionic surface-active agent and a liquid defoaming agent. The resultant foams are characterized by a majority of large size cells and membranes which themselves are formed with small cells. In addition, large amounts of many water-soluble or water-dispersable materials such as cellulosic pigments dyes, enzymes or the like may be added to the aqueous reactant. By homogeneously distributing these materials in the aqueous reactant they may be distributed throughout the finally prepared foam. However, the large cell size and membranes characteristic of the hydrophilic polyurethane sponges do not possess the necessary properties of tack, elasticity, sealability and flexibility needed in an ostomy gasket.
An ostomy gasket possessing varying degrees of tackiness, lubricity, and softness is disclosed in U.S. Pat. No. 3,980,084. The polymeric ostomy sealing gasket therein disclosed is formed by the polymerization of a hydroxyalkyl acrylate or methacrylate in the presence of a polyalkylene glycol, reducing agent, or chain terminator, and water. In manufacturing the gaskets, it is essential that the polymerization reaction be carried out in the presence of water. In this manner, a considerable quantity of water is absorbed into the polymer matrix during the polymerization reaction. In addition, natural or synthetic gums or cellulosic type materials to increase absorptive capacity may be incorporated into the polymer matrix. However, the material disclosed has a very low elongation at break and will not return to its original shape after deformation. In addition the materials are often highly viscous and therefore lack the sealability preferred for use in an ostomy device which may result in leakage around the ostomy seal.
Another type of adhesive formulated especially for ostomy care is disclosed in U.S. Pat. No. 4,393,080, and includes a pressure-sensitive adhesive material together with a polymer capable of developing elastomeric properties when hydrated.